288 



PHILOSOPHICAL TRANSACTIONS. [aNNO \7Q7- 



Eenjus. Garcias ah Horto in Clasius's Exotics. 



Arbor Benzoini. Grim in Ephem. Acad. Nat. Curios. Dec. 2. Ann. 1. p. 370./. 31. Si/lvius in 

 Valn'ti/ii Hiatoiia SimpHcium. p. i87. 



Benzuin. Radermacher in Jet. Sac. Batav. vol. 3. p. 44. 



Benjamin or Benzoin. Marsdens Hist of Sumatra, p. 193. 



Laurus I'enzoin. Uoutluyn in Act, Harl. vol. 21. p. 265. t. 7. 



It is a native of Sumatra, 



Description. — Branches round, tomentose. 



Leaves alternate, footstalked, oblong, perfectly entire, acuminated, being, above smooth, beneath 

 tomentose, a palm long. Footstalks round, striated, channelled, tomentose, very short. 



Racemes axillary, compound, nearly the length of the leaves : Footstalks common tomentose ? 

 partial alternate, spreading, tomentose : Pedicels or Stalklets very short. Flouers on one side. 



Calijx campanulated, very obscurely five-toothed, outwardly tomentose ; above a line in length. 



Petals five, (perhaps connat'^ at the base,) linear, obtuse, outwardly grey with very fine down, 

 four times longer tlian the calyx. 



Filaments ten, inserted into the receptacle, rather Sorter than the petals, beneath connate into a 

 cylinder of the length of the calyx, ciliated on the upper part below the anthers. 



Anthers linear, longitudinally adnate to the petals, and shorter by half than they. 



Germ superior, ovate, tomentose. Style filiform, longer than the stamens. Stigma simple. 



XXXI I. Of an Experiment on Heat. By George Fordyce, M. £>., F. R. S. 



p. 310. 



Heat, changes the qualities and appearances of matter in various ways. It is 

 also a powerful agent in many of the operations which mankind employ to fit 

 matter for their use. Though the ancients performed many of these operations 

 with a considerable degree of accuracy, yet there are many which they were 

 totally unacquainted with, and others, they brought to little perfection. One 

 principal cause was their having no means of measuring heat accurately. Van 

 Helmont was the first who found the mode of measuring heat by expansion. 

 His measure was an air thermometer, which is described in his Dissertation, 

 named " Aer," cap. 12. Since his time, various improvements have been made 

 on thermometers; many are still wanted. This instrument is however the foun- 

 dation of modern discoveries on this subject. The ancients were acquainted with 

 the manner of heating bodies by communication, by friction, by burning fuel, 

 by the sun, by fermentation, and the taking place of chemical combinations in 

 other cases. Boyle found, that melting a solid body produced cold (Experimental 

 History of Cold, title 1, chap. 18): Dr. Cullen, that cold was also produced by 

 converting bodies into vapour. It has been since that time found that the oppo- 

 site condensations, viz. of vapours into fluids, or fluids into solids, generate 

 heat. Cramer was the first who took notice of the different conducting powers 

 of different bodies, in his " Ars Docimastica," p. 1, § 274, Scholium. 



The power of animal bodies, of resisting the cold of the medium they are in, 

 has been long known. Mr. Ellis took notice of their being also able to resist 



